China said it does not recognise the tribunal and has refused to take part in the hearings. China has been projecting its growing naval reach while the United States is deepening ties with both traditional security allies such as Japan and the Philippines and with newer friends, including Vietnam and Myanmar.
What's the Philippines' case against China?
China's state-run Xinhua news agency said the "law-abusing tribunal" had issued an "ill-founded award".
"Such an illegal verdict is nothing more than a piece of waste paper", it said. However, China has already said interference of third parties will only exacerbate the tensions in the South China Sea. This rule of law is enshrined in the United Nations Charter.
However, disagreements between the littoral states started turning outright hostile in 2013 when China began materializing its respective claims by aggressively building artificial islands in the South China Sea and militarizing these islands.
But the ruling will impact both China and the Philippines.
Should the geographical features be ruled not to be islands, China's entire claim to the South China Sea is at stake, as is its claim to the so-called "nine-dash line", added Baker.
Philippine Foreign Minister Perfecto Yasay told AFP on Friday that Manila hoped to open direct talks with Beijing on the dispute, and presidential spokesman Ernesto Abella said Tuesday: "The top priority will be national interest".
He said: "The Philippines reiterates its abiding commitment to efforts of pursuing the peaceful resolution and management of disputes with the view of promoting and enhancing peace and stability in the region". Overlapping claims in the sea were for centuries merely a matter of grumbling rivalry - until recent times when China commenced reclamation work on the Spratly Islands chain, starting modestly and then shifting into full development mode.
Beijing reiterated that it will not accept the forthcoming ruling of a United Nations (UN) arbitral tribunal, citing that the arbitration case initiated by Manila was "illegal from the very beginning".
Nationalist protests are not rare in China, sometimes apparently with the tacit backing of the authorities.
"China should stop bullying its neighbours".
Chinese coast guard ships also surrounded another disputed area, the Second Thomas Shoal, which has been guarded by Filipino marines on board a grounded rusty warship.
However the tribunal and the PCA have no means to enforce the verdict, with compliance left to the parties concerned.
China and ASEAN member countries should still pursue cooperation despite the incoming global ruling on the case filed by the Philippines against the Middle Kingdom, an expert said. Centred on the Spratlys archipelago, which straddle vital worldwide shipping lanes, tensions in the South China Sea have simmered for decades, intensifying in recent years. This ambiguity has led to the idea among many ordinary Chinese people that it marks the nation's maritime boundary, but again, Beijing has never made this explicit. The post followed online rumors that reservists in central Chinese provinces were called up for an unspecified mission from July 10-22. While China may not like this week's ruling of the PCA, it will be a first step towards clarifying claims in the South China Sea and perhaps putting an end to ambiguity and insecurity in the region.